There is ongoing interest in increasing the use of unlicensed spectrum. There is special interest in aggregating unlicensed spectrum to licensed spectrum, in order to increase resources of a network when needed. Licensed assisted access (LAA) allows access to unlicensed spectrum via unlicensed component carrier, with assistance from primary component carriers (PCC) operating on licensed spectrum. LAA aims to port the Mobile Broadband (MBB) air interface to the unlicensed spectrum through aggregating unlicensed component carriers (CCs) at the operator's small cells. Small cells (also referred to as low power nodes (LPNs)) are low-powered radio access nodes that may operate in both the licensed and unlicensed spectrum, and have a relatively short coverage range (e.g., within 200 m from antenna(s) of the small cell). The 5 GHz unlicensed spectrum, in which WLAN is a prominent incumbent, is of special interest.
It is important for a technology, such as LAA, to access unlicensed spectrum in a fair and efficient manner, so that satisfactory intra-operator or inter-operators coexistence performance as well as satisfactory coexistence performance with incumbent WLAN may be achieved. With the envisioned dense deployments and/or high channel occupancy of WLAN, e.g., IEEE802.11ac, and LAA networks, it is more challenging to attain coexistence fairness.